279Views8Replies

Author Options:

Is there anyway to chage the Amperage rating on a power adapter? Answered

8 Replies

user
CameronSS (author)2009-05-04

No. The amperage rating is the maximum current that the components can handle without overheating and melting. You would have to replace everything, making it a new adapter anyway. That said, if you run .55A through an adapter rated for .50A, you probably won't fry it, it will just get hot.

Select as Best AnswerUndo Best Answer

user
jtobako (author)CameronSS2009-05-05

Well, there is, but it takes a bit of work and looking. The amp rating is more to protect the device powered rather than the charger (to a limit). If it has a transformer, you have to unwrap it enough to find the current limiting resistor and replace it. In a solid state power adapter I'm not sure but I believe that you have to replace the resistor? that's acting as a control on the voltage regulator.

Select as Best AnswerUndo Best Answer

user
gmoon (author)jtobako2009-05-05

The amp rating is more to protect the device powered rather than the charger (to a limit).

Not really. While the isolation offers a certain amount of protection to you, the current ratings of power adapters have more to do with their inherent limitations: the size of the wire, the number of turns, the core size, etc. Exceed the rated amperage, and the wire melts.

A power adapter that protects the device by failing catastrophically is a very poor marketing tool...

And generally there are no current limiting resistors in wallwarts. They might have one if they employ zeners, but usually the internal resistance (DC resistance) of the transformer is enough.

Select as Best AnswerUndo Best Answer

user
jtobako (author)gmoon2009-05-05

Then what's the resistor hidden under the wrapping on the transformer for?

Select as Best AnswerUndo Best Answer

user
AndyGadget (author)jtobako2009-05-05

It's probably not a resistor but a small mechanical thermal cutout so the output will be switched off for a time if the windings overheat. It will click back in when things have cooled down.

Select as Best AnswerUndo Best Answer

user
kelseymh (author)jtobako2009-05-05

If you want your response to be read by the original author (or if you want it to be marked "Best") you really must use the Answer it! link to put it at the top level. What you've done by using REPLY it to simply respond to Cameron's comment.

Select as Best AnswerUndo Best Answer

user
jtobako (author)kelseymh2009-05-05

I get an e-mail if I comment on someone's comment, but the author doesn't? And I don't really care about being "besteded" : )

Select as Best AnswerUndo Best Answer

user
AndyGadget (author)2009-05-05

The power rating on an adaptor means you can draw UP TO the current stamped on it. So a 500mA adaptor would be fine for powering a device which took 200mA, but not 800mA.
If you need more than the current marked, use a bigger adaptor.

Select as Best AnswerUndo Best Answer